In dentistry, luting materials based on composites are frequently used for the cementation of dental restorations such as crowns, bridges, inlays on the hard tooth substance. By dental composites are generally meant multisubstance systems which consist of an organic monomer or polymer matrix in which one or more fillers are incorporated. For a satisfactory bond to the hard tooth substance, the luting composites are used in combination with an acid dentine adhesion promoter, i.e. before the application of the composite the hard tooth substance is treated with the acid dentine adhesion promoter.
The treatment procedure is simplified if the dentine adhesion promoter is dispensed with and the luting composite can be used alone. These so-called self-bonding or self-adhesive luting composites also contain, in the monomer matrix, acid monomers which make possible a bond to the hard tooth substance. Frequently these are dual curing systems which, in addition to a photoinitiator for light-induced curing, include an initiator system for self curing at room temperature. The self curing of the luting composite is necessary above all if the restoration to be attached (e.g. crowns, bridge) is very opaque (e.g. zirconium oxide) or even lightproof (e.g. metal).
Generally, the self-adhesive luting composites are powder/liquid-based systems which are very storage-stable as parts of the initiator system can be coated onto the powder. As powder/liquid systems are complicated to use, and require a mixer for admixing, the mixing process frequently leads, at high speeds, to inclusions of air and, with regard to the filling quantity, have no great variability, these are not among the preferred delivery forms.
A paste/paste preparation has the advantage that no special additional apparatus is required and any desired quantity of fixing material can be admixed without problems. Recently, some materials with this basis have come onto the market, but common to all is that the dentine adhesion properties of these commercially available systems fall well short of those of powder/liquid systems, and most of these paste/paste preparations display almost no dentine bonding after self curing without subsequent light curing. The known paste/paste-based luting composites also frequently cause problems of storage stability, in other words the dentine adhesion properties are no longer guaranteed after the pastes have been stored for a prolonged period.
EP 1 479 364 A1 and EP 1 502 569 A1 describe self-adhesive paste/paste dental materials which are self curing or dual curing. It was sought in these applications to improve storage stability by using special initiator systems and dividing them between the two pastes. A combination of a hydroperoxide with a specific substituted thiocarbamide is used in EP 1 479 364 A1, and in EP 1 502 569 A1 combinations of oxidants such as hydroperoxides, Cu(II), Fe(III), Co(III) salts, persulphates and permanganates with reducing agents such as e.g. sulphinates, thiocarbamide, substituted thiocarbamides, ascorbic acid and its derivatives, barbituric acid and its derivatives, thiobarbituric acid and its derivatives, Fe(II), Cu(I) and Co(II) salts are disclosed. Generally, in both applications a large number of different fillers are described without preferred fillers being highlighted, nor is the allocation of the fillers to the respective paste of the two-component system a subject of the teaching. The dentine adhesion values after curing described in EP 1 4 79 364 A1 and EP 1 502 569 A1 cannot be achieved in practice. In particular dentine bonding values of only 0 to 2 MPa can be achieved after storage.